When a breakdown or disruption of the hydraulically controlled actuator, generally in the form of a hydraulically operable working cylinder, occurs, for example as a result of current interruption, the actuator can usually no longer be operated. Those occurrences can lead to dangerous disturbances, especially in areas relevant to technical security and/or safety, such as in nuclear power plants or the like. Conventionally, in such operation emergency situations, separate and independent emergency operation systems are activated. However, these emergency operation systems are costly to manufacture and set up, and generally are located so far removed from the site of disturbance that the emergency operation cannot be directly monitored by the operator.
DE 33 44 132 C2 discloses an operation device for a hydraulically controlled actuator which has a housing incorporating a fluid container connected through one connection point to the actuator and through another connection point to a supply circuit. Within the fluid container, a separating piston is guided longitudinally slidably by a manually operable adjusting device in the form of a pump handle. The pump handle cooperates with a mechanically working control device working separately in the form of a sliding piston to generate a through-flow opening connecting the fluid connection points with one another.
When this known arrangement is provided for emergency actuation of the hydraulically controlled actuator, no conclusions can be derived from the setting of the pump handle regarding whether an operationally secure and/or safe emergency operation has taken place or not. The known control device in the form of the longitudinally movable sliding piston is controlled exclusively by the fluid pressure, leading to erroneous control of the known control device and independent of the setting of the separating piston controlled by the pump handle. Additionally, because of the plurality of parts in the known solution, it is costly to manufacture.